Control device for roller mill



May 16, 1961 E. ROTH 2,984,423

CONTROL DEVICE FOR ROLLER MILL Filed Aug. 15. 195'? 2 Sheets-Sheet 1 INVEN TOR:

ERA/$7 B H B) Siva ML lu's Ellen-e7 May 16, 1961 E. ROTH 2,984,423

1 CONTROL DEVICE FOR ROLLER MILL Filed Aug. l5, 195'? ZSheets-Sheet 2 Fig.3

INVEN TOR:

7' ROTH All: fifforn a CONTROL DEVICE FOR ROLLER MILL Ernst Roth, Uzwil, Switzerland, assignor to Gebrueder Bnehler, Uzwil, Switzerland, a Swiss firm Filed Aug. 15, 1957, Ser. No. 678,377 Claims priority, application Switzerland Aug. 23, 1956 Claims. (Cl. 241-37) For the control of grinding roller mills, feeling elements are known, which are drawn downwardly by the weight of the goods. Said feeling elements generally are arranged in the intake tube, but do not indicate whether the goods are distributed over the entire length of the .feed roller. Further, there is no possibility of adjusting the time of response of the device by adjusting the feeling element, although said time of response should be of different length according to the quantity of goods to be ground. In a grinding roller mill which processes a larger quantity of goods, the engagement and disengagement of the grinding rollers should be effected in a shorter time than in a grinding roller mill working up a smaller quantity.

My present invention affords means which avoid the above-mentioned disadvantages and relates to a control mechanism for engaging and disengaging the grinding rollers. The present invention is characterized in that a feeling element is disposed on a lever in the feed chamber of the roller mill below the intake tube, the position of said lever being at least approximately horizontal and transmitting the force by which the goods act on the feeling element, at a high ratio on to a pilot valve.

Several embodiments of the invention are schematically illustrated in the drawing, in which:

Fig. 1 is a side view of a rolling mill, the frame and the means for reciprocating the movable grinding roller being shown in vertical section with certain parts of the control mechanism omitted;

Fig. 2 is a section taken at right angles to the section of Fig. 1, the movable grinding roller having been omitted and the feeling element being shown in two diflferent positions;

Fig. 3 is an enlarged view of the feeling element, further showing the pilot valve in vertical section;

Fig. 4 is a view of the feeling element and pilot valve as seen from the left-hand side of Fig. 3;

Fig. 5 is a plan view of the feeling element;

Fig. 6 is a side view of another embodiment of the feeling element; and

Fig. 7 is a plan view of Fig. 6.

In the frame 1 (Figs. 1 and 2) are mounted the feed rollers 2, 3 together with the feed segment 4. The goods to be ground issue from the intake tube 5 and accumulate in the space 6 above the feed roller 2 and in front of the feed segment 4. From the feeding roller 3, the goods drop between the fixed grinding roller 7 and the loose grinding roller 8 which is carried by levers 9 which at one end, at 10, are pivoted to the frame 1 and, at the other end, are actuated by the pistons 11 against the force of restoring springs -12.

In the space 6 on the side wall of the frame 1 is mounted a feeling device for controlling the engaging and disengaging actions of the loose grinding roller 8. This feeling device comprises a pilot valve 15 which is mounted in frame 1. To valve 15 is pivoted a feeling element (Fig. 3) consisting of an arm 16 which is substantially horizontal, and of a piece of tube 17 which is movable on said arm and is provided with feeling pins 18. By ad- States Patent 6 vancing or withdrawing the tube 17, the length of the feeling element may be varied as desired. At the same point at which the feeling element 16 is pivoted to valve 15, a substantially vertical arm 19 also is pivoted to the latter and carries a counterweight 20. The latter is movable on its supporting pin 21. The angle between the arms 16 and 19 and, thus, the feeding height of the feeling device is adjustable by means of a set screw 22. In Fig. 2 for example, two positions of adjustment of the arm 16 are shown. When the mill has to grind a greater quantity of goods per hour, the lower position of adjustment is chosen in order to attain a quick response of the control mechanism. Thus, by adjusting the position of tube 17 on arm 16, the portion of the intake goods contacted by the feeling element can be regulated or adjusted.

The goods 24 in space 6 bear down upon the feeling pins 18 and, thus, upon the lever system 16, 19. By virtue of the counterweight 20, the dead weight of the feeling element 17, 18 is balanced when it is properly adjusted in its position. The pressure of the goods is transmitted, at a high ratio, on to the valve spindle 25 against the force of a spring 26. To valve spindle 25 are secured two valve lids 28, 29 between which is situated a chamber 30 which communicates with piston 11 via a conduit or line 31. Valve lid 28 is capable of blocking the path from chamber 30 to a conduit or line 33 which is connected to a pressure source such as a pump 15a. Further, valve lid 29 is capable of blocking the path from chamber 30 to a line 34 which is connected to the tank 15b, the latter supplying pressure medium to the pump 15a.

When there are no goods in space 6, spring 26 pushes valve lid 28 against its seat. Valve lid 29 opens the path between piston 11, line 31, chamber 30 and line 34 to the drain. The loose grinding roller 8 is disengaged.

When the goods press against the feeling element, the movement of the latter is transmitted on to valve spindle 25. Valve lid 29 bears down on its seat. Valve lid 28 opens the path from line 33 of the pressure source via chamber 30 to line 31 and piston 11 and the loose grinding roller 8 is engaged (Fig. 3).

Tube 17 of the feeling element may be provided with inclined feeling plates 36 in lieu of feeling pins, as shown in Figs. 6 and 7.

What I claim as new and Patents, is:

1. In a grinding roller mill for granular goods and the like having an intake for the goods, a frame defining a feed space communicating with and disposed below the intake for receiving the goods, at least one feed roller mounted in said frame and located in said feed space, the roller having a substantially horizontal axis and an end, a fixed grinding roller mounted in said frame at a level below the feed roller, a second grinding roller mounted in said frame and movable with respect to said fixed grinding roller, cylinder and piston means operatively connected with said second grinding roller and adapted to move the latter toward said fixed grinding roller, means for constantly urging the second grinding roller away from the fixed grinding roller, 21 source of pressure, conduit means connecting said source with the cylinder and piston means for delivering a pressure medium thereto whereby to move the second grinding roller toward and into grinding contact with the fixed grinding roller, and a pilot valve in said conduit means for shutting off the flow of pressure medium to said cylinder and piston means when there are no goods in the feed space, the improvement which consists in the provision of a control mechanism for the pilot valve, said control mechanism comprising an elongated arm in said feed space, the arm having one end connected to said frame adjacent to the end of said feed roller, said arm being disposed desire to secure by Letters above and substantially parallel with the axis of said feed roller; and a feeling element supported by said arm, the arm and the feeling element being pivotable in a vertical plane by the goods introduced into said f eed space for operating the pilot valve whereby to permit the flow of pressure medium to said cylinder and piston means.

2. The control mechanism as set forth in claim 1, further comprising means for adjusting the position of said arm with respect to the axis of said feed roller to give adjustable operating positions of the pilot valve.

3. The control mechanism as set forth in claim 1, wherein said feeling element comprises a tubular member with projections thereon, the tubular member being slidably supported by and receiving said arm, whereby the position of said feeling element may be adjusted by sliding same along said arm and the projections may thus contact different portions of the intake goods.

4. The control mechanism as set forth in claim 1, further comprising a substantially vertical arm having an upper end pivotably fixed to the end of said first mentioned arm; means operatively connected with one of said arms and engaging with the other of said arms for supporting said first mentioned arm in substantially horizontal position; and a counterweight fixed to said vertical arm for balancing the weight of said first mentioned arm and of said feeling element.

5. The control mechanism as set forth in claim 4, wherein said last mentioned means comprises means for pivoting said first mentioned arm with respect to said vertical arm and against the force of gravity.

References Cited in the file of this patent UNITED STATES PATENTS 

